Expand the Possibilities of the SiloPatrol® Through the Selectionof Plumb Bobs

Even Some Liquids...That's Right, Liquids!

The SiloPatrol® SMU SE is a durable weight and cable (plumb bob) based continuous level measurement sensor that is unaffected by application factors such as humidity, dust, spurious reflections, dielectric constant and conductivity.

Inverted Plumb Bob

Solid / Water Interface Plumb Bob

Ball Float Plumb Bob

A variety of optional plumb bobs are available to make the SiloPatrol® effective for a wide range of general and specialized applications. The standard aluminum plumb bob works well for a large variety of powders and bulk solids; However, there are some more particular applications that may require a different style of plumb bob in order to properly interact with a specific target material. For instance, there is the inverted plumb bob for level indication of lighter bulk solids (ex. expanded perlite) or fluidized powders. There is the solid / water interface-style plumb bob to provide level measurement for settled solids in a blanket of water.

In addition, a stainless steel ball float style plumb bob is available for use with some liquids. A Teflon® version of the ball float is offered for sticky or corrosive materials.

Q...Just wondering what you would suggest for a sensor in a 27 ft. (8.2m) silo that holds ground plastic that is under 3/8 inch (1cm) in size? The silo is made of steel and it has a cone on the bottom. We would also like to bring in a signal to our control system.

SafePoint® Fail-Safe Level Indicator

A...For a high or low point level indicator, our first recommendation would be the TrueCap RF Capacitance level sensor. This is a fully electronic unit with no moving parts and superior sensitivity of material detection. There are also a variety of probe configurations to fit a specific application (See below article for more details). Another recommendation would be a rotary paddle level sensor like Monitor's Model KA/KAX. This type of sensor has a history of being a reliable and affordable solution in plastic materials and other materials as light as 5 lbs/ft3 (80kg/m3). For added safety, Monitor's SafePoint® self-validating, fail-safe rotary paddle level sensor detects power loss and internal failure. It also includes an external status LED. Both the Model KA/KAX and the SafePoint have outputs that can be used to provide signals to your system.

If continuous level measurement is desired, we would recommend the SiloPatrol® weight and cable level sensor. The SiloPatrol is a durable, yet economical, continuous level sensor that is not affected by material characteristics like dielectric constant, conductivity, dust and humidity. It works well with plastic materials in vessels up to 150 ft (46m). An additional benefit is that this unit is easy to install. The 4-20mA analog version provides a signal that can communicate with existing PLCs. The smart RS-485 version includes Modbus connectivity to communicate with existing control systems that use Modbus. The RS-485 version can also be used with SiloTrack® inventory management software or HMI2 local operator interface. Since there is a cone at the bottom of the silo, having an accurate measuring / cable length is critical to ensure proper measurement and to prevent the plumb bob from going through the discharge opening and possibly damaging a rotary lock, slide gate, auger, etc.

Answer provided by Monitor's Technical Support Department

Please feel free to contact one of our technical support / application engineers at: techsupport@monitortech.com if you have questions regarding an application.

Interesting Facts ----------------------

On Plants and Trees...

There are around 400,000 identified plant species and the list is growing all the time.

The wide product selection is a major reason why Monitor's TrueCap® RF capacitance probe is a popular and versatile point level sensor for a large range of powder and bulk solid, liquid and slurry applications. Optional versions include high temperature, hazardous location, stub probe (pictured), food grade probe, quick-connect process connection, high level sensing with pipe or cable extensions and more.

For instance, the stub probe model (a shorter version of the standard probe) allows the TrueCap to be used in tighter spaces, used to limit mechanical forces placed on the probe from material flow or to keep the probe out of the main material stream. In addition, the TrueCap design provides automatic immunity to material build-up on the probe by its driven shield design. Options for the TrueCap® stub probe model include a 3/4 inch / 1-1/4 inch combination process connection for replacement or new installations and a probe with white nylon insulator for food grade applications.

Outside View of Unloading Pit and TrueCap® Level Sensor

Inside View of Unloading Pit and TrueCap® Level Probe

The photos above show a stub probe model of the TrueCap® installed in the unloading pit of a grain handling elevator set-up. The TrueCap sends a signal based on the system design requirements that involves the unloading pit connected to a drag conveyor that feeds the bucket elevator to move the grain to a silo. In this situation, the TrueCap stub probe version was chosen because the shorter probe will help to limit the amount of mechanical force on the probe from the material (grain) flowing into the pit.